Process for tanning with aluminium salts



o'rro Roma, or nanms'ranr, GERMANY, ASSIGNOR, BY

PATENT @FFHQE.

IVIESN'E- ASSIGNLMENTS, TO

THE CHEMICAL FOUNDATION, INC., A CORPORATION OF DELAWARE.

PROCESS FOR TANNING WITH ALUMINIUM: SALTS.

No Drawing.

T 0 all whom it may cancer-n I Be it known that I, @T'ro RQHM. a subject of the King of lVurttemberg, residing at No.

l6- lVeiterstiidterstrasse, in the city 01" declare that the following is a full, clear,

and exact description of the same.

Leather tanned 1n the usual manner w th V alum must be treated with Water before heing dyed, in order to. remove superfluous alum and common salt. It is well known that in doing so apart of the tanning substance is washed out of the outer layers of producing leather.

the leather, and particularly out of the grain. Owing to this nntanning, grain defects arise and the leather becomes insufliciently tanned and hard. In order to avoid this the leather had to be dried and kept for weeks and months in dry condition in order to more intimately unite the tanning substance with the skin. r

Now it has been found that this keeping of the leather dried with. an excess of tanning substance is not necessary if the skins are treated with a solution of a salt of the lower fatty acids. For this purpose the formates or acetates of the alkalies or earth alkalies, for example sodium formates, come particularly into question.

The treatment with these salts can take place at different stages of the process for If the sodium formate is added to the tanning liquor itself the same result is obtained, without having to store the leather in dry condition, as by the usual alum tanning process with this subsequent treatment. Further, the addition of wheat flour usual in making kid leather can either be entirely omitted or it can be replaced by finely powdered mineral substances, such as talcum, etc. Moreover the greasing can be decreased and in many cases entirely omitted.

If the sodium formate is not added to the tanning liquor itself the removal of tanning substances by the washing process after employing the usual alum process can be avoided by placing the moist leather taken out of the tanning liquor into the solution of a salt of the lower fatty acids. If it is desired to retain the usual alum. tanning process with the subsequent drying, because Specification of Letters Patent.

Patented July 4, 1922.

Application filed December 6, 1917. Serial No. 205,880;

'.the choice of the skins for White, black or colored leather is easier and more convenientin dry condition, the fatty acids are added-to the water used for washing the dried alum leather.

Examples. 1. Tamziny with mZum-l-saZt-l-sodiwn 7'01- wz-az e-l-talouma For every 100 kg. of depilated skins from which the liquid has been allowed to strain off 8 kg. alum-{ 2% kg. salt +500 sodium formate 10 kg. talcum+50 1. water are required. 7 In this tanning liquor the skins are'moved about for an hour and they are then allowed to lie in the same during the night. In the morning the skins are again moved about for a short time and they are then dried in the usual manner.

- 2. llashing 0 f alum tannpl moist fur with sodium f0rmates.-The furs tanned in the.

solved'in a little water are added, and the leather is moved about again for an hour. In this liquid the skins are allowed to lie for a few hours and they are then dried in the usual manner.

4. Washing dried furs with sodium formate.-10 kg. of dried alum tanned furs are placed in 40 to 50 liters of a 1% sodium formate solution or they are moved about in same until they are entirely soaked. They are allowed to lie in this liquid for some time and are then dried in the usual manner.

Claims.

' too 3. The process of tawing which comprises immersing hides or skins in a 1i uor containing alum, sodium chloride, so ium formate, talcum and water, moving the skins about in said liquor for a short time, allowing to remain in said liquor about fourteen hours, moving about in said liquor again for about one hour, and finally drying.

4. The process of tawing which comprises immersing hides or skinsin aliquor containing 8 kg. potassium alum, 2. kg. sodium chloride, 500 g. sodium formate, about 10 kg. talcum, and about 50 I. of water for each 100 kg. of hides or skins, moving the skins about in said liquor for a short time, allowing to remain in said liquor about fourteen hours, moving about in said liquor again for about one hour, and finally drying.

5. In the process of tawing the step, which comprises the employment of a solution containing a formate of an alkali metal.

'6. In the process of tawing the step which comprises the employment of a solution of sodium formate.

7. In the process of tawing the step, which comprises the employment of a liquor containing a formate of alkali metal and a finely powdered mineral substance.

8. In the process of tawing the step, which comprises the employment of a formate of an alkali metal, together with talcum.

9. In the process of tawing the step, which comprises the immersing skins in a liquor containing a formate of an alkali metal and a finely powdered mineral substance.

10. In the process of tawing, the step which comprises immersing skins in a solution containing a formate of an alkali metal and talcum.

11. A tanning composition including potassium alum, sodium chloride, sodium formate, talcum and water.

DR. OTTO RtlHM. 

